GCN Circular 45915

Subject

GRB 261011A: GMG Optical Observation

Event

GRB 261011A

Date

2026-10-12T01:58:20Z (2 days ago)

Edited On

2026-10-12T12:51:27Z (a day ago)

From

Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi@ynao.ac.cn>

Edited By

Judith Racusin at NASA/GSFC <judith.racusin@nasa.gov> on behalf of Rui-Zhi Li at Yunnan Observatories, CAS <liruizhi@ynao.ac.cn>

Via

Web form

R.-Z. Li, B.-T. Wang, F.-F. Song, J. Mao, K.-X. Lu, J.-G. Wang and B. Wang (YNAO, CAS) report:

We observed the field of GRB 261011A (Huang et al., GCN 45895

; Cenko et al., GCN ; T0 at 2026-10-11T13:46:41) using the GMG-2.4m telescope at the Lijiang Observatory. The observation began at 2026-10-11T16:41:50, about 2.92 hours after the trigger.

The optical counterpart reported by Swift-UVOT (Cenko et al., GCN 45896

) and by other facilities (O'Neill et al., GCN ; Fu et al., GCN ; Izzo et al., GCN ; Wu et al., GCN ; Yin et al., GCN ; Shi et al., GCN ; Aryan et al., GCN ; Arya et al., GCN ; Izzo et al., GCN ; Huang et al., GCN ; Bochenek et al., GCN ) was detected in an r-band image.

The preliminary analysis results are shown as follows:

Start time [UTC]	Exposure [s]	Tmid-T0 [h]	Filter	AB Magnitude	5-sigma U.L.
2026-10-11 16:41:50.018	300	2.961	r	20.46 ± 0.04	22.2

The given magnitudes are derived based on calibration against Legacy Survey DR10 field stars, and are not corrected for the expected Galactic foreground extinction, corresponding to a reddening of E(B-V) = 0.019 mag in the direction of the optical counterpart (Schlafly & Finkbeiner 2011).